What is Hemoglobin A1c?

If she makes it through the nomination process, Judge Sonia Sotomayor would not only be the first Hispanic to sit on the U.S. Supreme Court, she would also be the first member with type 1 diabetes.

At age 8, Sotomayor was diagnosed with the chronic condition, which reduces her life expectancy by five to 10 years relative to her peers. And because the disease also puts individuals at risk of cardiovascular problems, kidney failure, nerve damage and even blindness, there has been some concern about ability to fulfill her role as a justice.

But on Thursday, a letter from Sotomayor's longtime physician, Andrew Drexler of the David Geffen School of Medicine at the University of California, Los Angeles, surfaced, allaying many of these concerns. Drexler wrote that Sotomayor "always had excellent control of her diabetes" and that "her hemoglobin A1c levels, the best measure of diabetes control, have consistently been less than 6.5 percent, the optimal level defined by all diabetes organizations." Drexler also noted that he does not expect her to develop any of the more serious complications of diabetes.

To find out more about diabetes and what Sotomayor's A1c levels really mean for the future of the Supreme Court, we spoke with Mark Schutta, an endocrinologist and medical director of the Penn Rodebaugh Diabetes Center.

[An edited transcript of the interview follows.]

What is type 1 Diabetes?
Diabetes is basically a disease where patients have an inability to make insulin. Insulin allows glucose to go from the bloodstream to the cells, where it is used as fuel. Type 1 diabetes is an autoimmune disease where the body destroys the beta cells of the pancreas: the cells that make insulin. There are several theories about its cause, including a virus or a genetic predisposition set off by an environmental trigger. It presents itself very acutely and is treated with insulin at the time of diagnosis.

What is a hemoglobin A1c test?
It represents the percentage of glucose that binds to hemoglobin in red blood cells. Because red blood cells live for about 90 days, the test gives you a good snapshot of a patient's glucose control.

Is Sotomayor's A1c healthy?
6.5 percent represents excellent control of diabetes. The American Diabetes Association recommends an A1c less than 7 percent, although they advocate that patients strive for an A1c as low as possible. The American College of Endocrinology advocates less than 6.5 percent. In reality, it's an age-dependent test, and a healthy 20-year-old person is probably at 5 percent, while there are poorly controlled patients with poor medical care who are as high as 10 to 14 percent.

The facts are that diabetic patients have a shorter life expectancy of about five to 10 years, and diabetes as a disease is the fifth leading cause of death.
How do you control it?
The standard of care is for patients to receive basal insulin injections once or twice a day, and at meal time they receive rapid-acting insulin to help them take care of the spike in blood sugar levels. One issue is the downside of insulin in that it can induce hypoglycemia [low blood sugar]. That's why it's important for patients to monitor blood sugar levels and make sure they're staying within an acceptable range.

Sounds like a lot of work. Do you think Sotomayor's diabetes should disqualify her as a Supreme Court nominee?
Absolutely not. Diabetes is challenging disease to live with, but it is also a completely manageable disease. It doesn't preclude anybody from accomplishing anything or participating in any activity.